Inflammation is a response of vascularized tissue to injury; it is perceived as redness, heat, swelling, and pain and is usually accompanied by loss of function to varying degrees. In its acute form it is of short duration, involving increased vascular transudation and interstitial edema and infiltration of inflammatory cells, predominantly of neutrophils. In moist mucosal tissues, such as that which lines the respiratory tract, there may also be loss of surface epithelial cells and secretion of mucus. This form of inflammatory response is considered protective and is, therefore, in the short term, beneficial to the host. However, if the injury is repeated or severe, the character of the inflammatory infiltrate may change to one predominantly of mononuclear cell (i.e., lymphocytes, monocytes, and macrophages) and it may become persistent.
Inflammatory diseases afflict millions of people across the world leading to suffering, economic loss and premature death. As well as inflammatory lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), other inflammatory diseases include allergic rhinitis, rheumatoid arthritis, osteoarthritis, inflammatory bowel disease, and psoriasis. Inflammatory sinus diseases include sinusitis due to infections of acute, subacute and chronic duration; allergic rhinitis; and inflammation due to other underlying causes such as allergies, hay fever, allergic rhinitis, rhinitis, and asthma, affecting the nasal cavity or the four sinuses, each which have left and right halves, the frontal sinuses, the maxillary sinuses the ethmoid sinuses, and the sphenoid sinuses.
Chronic inflammation may develop from unresolved symptomatic acute inflammation or may evolve insidiously over a period of months without apparent acute onset of clinical manifestations. Histopathologic features of chronic inflammation include the predominance of macrophages and lymphocytes, proliferation of nurturing structurally heterogeneous and hyperpermeable small blood vessels, fibrosis, and necrosis. Activated macrophages and lymphocytes are interactive in releasing inflammatory mediators or cytokines that amplify immune reactivity. Cytokines include a family of biologic response modifiers including interleukins, chemokines, interferons, growth factors, and leukocyte colony-stimulating factors. The cytokines are secreted by leukocytes, connective tissue cells, and endothelial cells. Chemokines consist of 8- to 10-kd proteins that stimulate leukocyte recruitment and migration as part of the host response to antigenic insults. In chronic inflammation, the protracted inflammatory response is often accompanied simultaneously by tissue destruction and repair.